Method of fabricating connecting leads



June 24, 1941. E, amp-F 2,246,931

METHOD- OF FABRICATING CONNECTING LEADS- Filed Jan. 26, 1939 INVENTOR. [DA RED (fl/FIT) ATTORNEY.

Patented June 24, 1941 METHOD OF FABRICATING CONNECTING LEADS Edward Chiffey, Harrow, England, assignor to Electric & Musical Industries Limited, Hayes,

Middlesex, Britain England, a company of Great Application January 26, 1939, Serial No. 252,911 in Great Britain February 1, 1938 1 Claim.

The present invention relates to the method of fabricating connecting leads for electrical apparatus, and particularly, but not exclusively, to connecting leads for condensers and resistances such as those used in wireless apparatus.

In constructing condensers of the small fixed capacity type it is customary to form the plates of thin metal foil and to allow a certain portion to extend at each end of the condenser to form terminal members. The projecting portion of the foil is in itself too frail to be used for connecting the condenser in an outside circuit and some additional means for making such connection must be provided.

I order to facilitate the fitting of this type of condenser into circuit with other components it is desirable that the connecting leads should be capable of being bent in all directions.

It has already been proposed to form connecting leads for electrical condensers by stamping them out from thin sheet metal, but leads formed in this manner suffer from the disadvantage that it is only possible to bend such leads on an axis lying in or nearly in its plane and not about an axis lying well outside it.

It has also been proposed to form connecting leads for electrical resistances by bending up a flat metal member into the form of a wire with a flat portion at one end. This form of connecting lead suffers from the disadvantage that acid used in the preliminary stages of a plating process after the metal member is bent to the required form creeps into the hollow wire and remains after the article is completed. This acid left in the small bore of the wire causes corrosion.

It is, therefore, an object of the present invention to provide a method to construct connecting leads for electrical apparatus and particularly leads for condensers and resistances for wireless apparatus with a View to reducing the above disadvantages.

According to the invention, a method of fabricating connecting leads for electrical apparatus comprises forming a head or enlarged portion on the end of a length of wire, then flattening this head or enlarged portion to form a connecting lug.

In its preferred form the head or enlarged portion on the wire is prior to flattening of frustoconical shape and tapers towards the wire stock.

In order to overcome any brittleness which occurs through the flattening process the leads may be annealed.

In order that the invention may be more fully understood, it will now be described with reference to the accompanying drawing, in which:

Figure 1 shows a headed wire; and,

Figures 2 and 3 show the connecting lead formed by flattening the headed wire shown in Figure 1.

Referring to Figure 1, a length of wire stock of brass or other good conducting metal is provided with a head 2 having a conical portion 3 which tapers towards the wire somewhat like an ordinary pin head. The diameter of this head is preferably about three times the diameter of the wire. This head may conveniently be formed on the wire stock by the usual knocking up process employed in pin making.

The head 2 is then flattened in a suitable press such that it is made thinner than the wire, and takes the form of a substantially circular lug which gradually tapers towards the wire stock as shown at 4 in Figures 2 and 3. The metal in the head is sufficient to permit the flattened portion to be of considerable width compared with the diameter of the wire stock, so that a large area is available for connection to the electrical apparatus by soldering or by other suitable connecting processes.

The ends of the leads during the flattening process may tend to become brittle, and in such case it will be found desirable to subject them to a simple annealing process.

The connecting leads are preferably tin-plated in order to prevent corrosion and to simplify soldering.

The wire stock may be of the order of 20 s. W. G. and the head may be formed so that its diameter is about three times the diameter of the stock. The width of the flattened head may be about Since the connecting lead is constructed from wire stock, the lead may be readily bent in any direction.

I claim:

The method of fabricating connecting leads for electrical apparatus which consists in forming on the end of a length of wire used as the connecting lead itself a head portion of frusto-conical formation which tapers towards the wire stock, and then flattening said head portion to form a connecting lug.

EDWARD CHIFFEY. 

